As we move from stage 1 sleep to stage 4 sleep, the brain emits successively waves. smaller, faster larger, slower smaller, slower larger, faster

slower larger

A complete sleep cycle lasts between 90 and 110 minutes where your body passes through stages 1, 2 3, 4, and REM  where there is  "rapid eye movement".  Stages 1, 3, and 4 together account for r 30% of your sleeping hours, 20% REM and Stage 2 (50%).

As we move from stage 1 sleep to stage 4 sleep, the brain emits successively slower larger waves.

Stage 1 consists of very light sleep.  In this stage, your brain emits alpha waves (whose frequency ranges from 8 to 13 hertz) to theta waves (4–7 Hz).  The theta waves are slower and greater in amplitude (up-and-down movement).

In Stage 4, the brain emits almost all delta waves which are the slowest and highest amplitude brain waves.

the trait of personality falls in the middle of the diagram because personality is a mixture of ones nature and environment.